The present invention relates to an improved sub-surface direct exchange (also commonly referred to as “direct expansion”)/geothermal tubing installation means, so as to enable only one man to install vertically oriented sub-surface heat exchange fluid transport tubing, utilized in direct expansion/water-source/geothermal heating/cooling system designs, together with an optional means to pressure test all brazed/welded/fused tubing joints as they are made, prior to final tubing/line installation completion, for use in association with any geothermal heating/cooling system, or partial geothermal heating/cooling system, utilizing sub-surface vertically oriented heat exchange elements as a primary or supplemental source of heat transfer.
Geothermal ground source/water source heat exchange systems typically utilize fluid-filled closed loops of tubing buried in the ground, or submerged in a body of water, so as to either absorb heat from, or to reject heat into, the naturally occurring geothermal mass and/or water surrounding the buried or submerged tubing. Water-source heating/cooling systems typically circulate, via a water pump, a fluid comprised of water, or water with anti-freeze, in plastic (typically polyethylene) underground geothermal tubing so as to transfer heat to or from the ground in a first heat exchange step. Via a second heat exchange step, a refrigerant is utilized to transfer heat to or from the water. Finally, via a third heat exchange step, an electric fan is utilized to transfer heat to or from the refrigerant to heat or cool interior air space.
Direct exchange/direct expansion (“DX”) ground source heat exchange systems, where the refrigerant fluid transport lines are placed directly in the sub-surface ground and/or water, typically circulate a refrigerant fluid, such as R-22 or the like, in sub-surface refrigerant lines, typically comprised of copper tubing, to transfer heat to or from the sub-surface elements via a first heat exchange step. DX systems only require a second heat exchange step to transfer heat to or from the interior air space by means of an electric fan. Consequently, DX systems are generally more efficient than water-source systems because of less heat exchange steps and because no water pump energy expenditure is required. Further, since copper is a better heat conductor than most plastics, and since the refrigerant fluid circulating within the copper tubing of a DX system generally has a greater temperature differential with the surrounding ground than the water circulating within the plastic tubing of a water-source system, generally, less excavation and drilling is required, and installation costs are lower, with a DX system than with a water-source system.
While most in-ground/in-water heat exchange designs are feasible, various improvements have been developed intended to enhance overall system operational efficiencies. Several such design improvements, particularly in direct expansion/direct exchange geothermal heat pump systems, are taught in U.S. Pat. No. 5,623,986 to Wiggs; in U.S. Pat. No. 5,816,314 to Wiggs, et al.; in U.S. Pat. No. 5,946,928 to Wiggs; and in U.S. Pat. No. 6,615,601 B1 to Wiggs, the disclosures of which are incorporated herein by reference. Such disclosures encompass both horizontally and vertically oriented sub-surface heat geothermal heat exchange means.
The historical installation means and function of vertically oriented sub-surface fluid transport tubing in geothermal heating/cooling systems are well understood by those skilled in the art. However, such historical installation means virtually always requires at least two men to facilitate the installation. Typically, the men install the fluid transport tubing within a pre-drilled borehole/well to the desired depth, which depth may range from 50 feet to 500 feet, or more.
Generally, in water-source system applications, long lengths (typically 50 feet, or longer) of polyethylene tubing are butt-fused together and inserted into a borehole by at least two men, who insert the tubing manually and/or via machine.
Generally, in DX system applications, 50 foot lengths of soft copper are unrolled and then one of brazed and welded together and manually inserted into a borehole by at least two men. Even in the instances where common industry standard 20 foot lengths of hard, ACR grade, copper tubing have been utilized in vertical DX system testing applications, the installations have typically required at least two men. For example, one man would insert the tubing into the borehole while a second man would steady and guide the upper portion of the 20 foot tube and/or tubes while standing at an elevated location on a ladder, on scaffolding, or the like.
Further, historically in a DX system application, the copper refrigerant transport tubing within the borehole is typically only pressure checked for leaks, via a maximum system operational pressure test usually in the 300 psi to 600 psi range, once the complete refrigerant tubing assembly has been installed, prior to filling the empty space within the borehole with a heat conductive grout, as is well understood by those skilled in the art. Thus, if a leak is detected, the entire tubing assembly is subject to withdrawal, repair, and re-insertion, which can be quite time-consuming and costly.
Vertically oriented (herein meaning at least one of vertical and vertically angled, as opposed to horizontal) installation means of geothermal fluid transport tubing requiring two men is expensive and adds to the typically high costs of geothermal systems, thereby contributing to a marketing/sales impairment. Consequently, a means to provide an efficient manner in which to install vertically oriented geothermal DX, water-source, and the like, sub-surface heat exchange fluid transport tubing, as well as a means to pressure test each joint/coupling as it is made, would be preferable. The present invention provides a solution to these preferable objectives, as hereinafter more fully described.